Review on synthetic approaches towards barbituric acids‐based furo[2,3‐d]pyrimidines

Pyrimidine annulated five‐membered heterocyclic scaffolds containing oxygen as furopyrimidine, particularly furo[2,3‐d]pyrimidine derivatives are an important class of heterocyclic compounds in pharmaceutical discovery research. Furo[2,3‐d]pyrimidines are generally synthesized either from a pyrimidine derivative by constructing a furan ring on the parent pyrimidine ring or from a suitably functionalized furan ring by generating the pyrimidine ring on the parent furan ring. Moreover, there is a wide range of multicomponent reactions that include barbituric acids as starting material for the synthesis of these compounds. Also, the reaction of barbituric acids with alkenes, alkynes, aldehydes, ketones, ninhydrin, and chloroacetylchloride, and Cloke–Wilson rearrangement of spirocyclopropyl barbiturates afforded furo[2,3‐d]pyrimidine derivatives. This review is an attempt to compile the literature of various synthetic procedures toward barbituric acids‐based furo[2,3‐d]pyrimidine and spirofuro[2,3‐d]pyrimidines.